A punch-in element of this kind is known from EP-A-23022344. It is intended for punching into a single thick sheet metal part and is provided with a plurality of ribs at the outer periphery of the shaft part which extend in the axial direction along the shaft part from the sheet metal contact surface over approximately half the length of the shaft part.
Moreover, a rivet element is known from EP-A-1806508 which is equipped with a rivet section having ribs providing security against rotation extending in the longitudinal direction which extend over the full length of the rivet section. A strict distinction is, however, made in the area of functional elements or fastener elements between press-in elements on the one hand and rivet elements on the other hand and indeed because press-in elements are not intentionally deformed on attachment to the sheet metal part, whereas rivet elements are intentionally deformed in order to form the rivet bead which is important for the component assembly consisting of a rivet element and a sheet metal part. The design of the two types of functional elements or fastener elements is thus fundamentally different.
A further rivet element is known from EP-A-2177776. This element is also intended for attachment to a single pre-pierced thick sheet metal part. Its shaft part has a thick walled hollow section and a thin hollow rivet section at the free end. The thick walled section is provided with ribs extending in the longitudinal direction which extend over substantially the full length of the thick walled section, the rivet section is however not provided with ribs.
None of the above-described elements is intended for the attachment to a first and a second sheet metal part or designed for this. In practice, above all in the field of bodywork, applications are repeatedly arising in which a functional element has to be attached to a first and to a second sheet metal part, with the attachment to the first sheet metal part taking place at one location in a factory whereas the attachment to the second sheet metal part takes place at a different location in the same factory or in a different factory. The first sheet metal parts with the attached functional elements are frequently transported loosely in boxes from one location to the other and are thus subjected to jolts and frequently rough handling which can lead to a loosening of the functional element in the first sheet metal part, or indeed to the two parts falling apart, so that they are no longer fit for attachment to the second sheet metal part or can only be used with a great effort. This is a considerable problem, especially in mass production.
An example for such a component assembly is the attachment of hinges to door posts of vehicle bodies. The door posts are normally manufactured from a relatively thin sheet metal, in particular when they are part of the outer skin of the vehicle. It is then known to attach nut elements to a so-called boat, which is formed by a thicker sheet metal part, which frequently has a flat bent U-shape in cross-section and which is welded to the door post from the inner side for stiffening. In the design of the door hinges and the attachment to a door post, attention must always be paid to the fact that a relatively heavy person of for example 150 kg body weight can brace themselves against the door frame on climbing in and climbing out, whereby considerable lever forces have to be taken up by the door post without it deforming.